The present invention relates to a device for shading spaces and in particular for shading areas or plazas where people can walk, in desert areas, comprising a flexible roofing surface which extend on carrier elements at a spacing from the surface to be shaded, preferably with a roof skin or membrane which is stretched on supports. The present invention further relates to a shading device formed from a light plane load-bearing structure and having photovoltaic means to convert sunlight into electricity.
Still further the invention relates to an arrangement having a flexible surface for accommodating photovoltaic cells, in particular a roof skin which is stretched over frame members, for shading surfaces or areas, wherein the cells are adapted to be connected to a current collector or the like.
It is known for roofing structures of that kind to be made from stretched tent cloths or from netting materials in order in that way, during the daytime, to keep the spaces therebeneath for pedestrians, vehicles or the like at bearable temperatures. Such roofing structures can be used exclusively for the purposes of providing shade and must be capable of withstanding high temperatures, in accordance with the use for which they are intended.
An arrangement having a roof skin for accommodating photovoltaic cells is shown in German laid-open application (DES-OS) No. 34 27 574 which illustrates a roof, the outward side of which is fitted with photovoltaic elements of that kind. The structure of such a photovoltaic cell can be seen for example in German laid-open application (DES-OS) No. 30 13 991. That involves using what is known as the barrier-layer photo effect or the photovoltaic effect. It occurs as a junction within a barrier layer between semiconductor and semiconductor, semiconductor and electrolyte, semiconductor and metal or metal and electrolyte, or in the immediate vicinity of a barrier layer. Charge carrier pairs produced by incident light are separated in the electrical field of the barrier layer, thereby producing a usable voltage.
Now, it has been found in practice that flexible carriers for photovoltaic cells of that kind are admittedly desirable, but that the use thereof involves problems, in particular in regard to the mechanical forces acting on the arrangement.